The present invention relates generally to a cylinder head gasket for automotive internal combustion engines. More specifically, the present invention relates to a cylinder head gasket having an oil drain back tube fastener therein.
Overhead valve internal combustion engines include a cylinder block portion and a cylinder head which are bolted together. In a pushrod engine, the cylinder block includes at least one cylinder bore opening to an end face and a push rod cavity spaced from and generally parallel to the cylinder bore and opening to the end face of the cylinder block. In an overhead cam engine, there is an open timing chain cavity where the cylinder head and crankcase mate to a timing chain cover and oil drains back into the crankcase. The cylinder head includes a corresponding number of combustion chambers forming the top of the cylinder bores, at least one intake valve and exhaust valve allowing communication of each combustion chamber with intake and exhaust ports, respectively, valve springs, rocker arms, and a push rod cavity or timing chain cavity. The combustion chamber and push rod or timing chain cavity of the cylinder head open to an end face in alignment with their counterparts in the cylinder block.
A gasket is provided between the end faces of the cylinder block and the cylinder head to seal the interface therebetween. The gasket includes a cutout to surround the pushrod cavity and a plurality of bolt holes and cylinder bore apertures to mate with the cylinder bores of an engine block.
Combustion engines may also include oil drain tubes that drain oil from an air/oil separation unit into a crankcase. Known oil drain tubes are positioned external to the combustion engine, thereby requiring the oil drain tube to be configured to avoid packaging issues and complicating assembly issues. Therefore, it is desirable to route an oil drain tube through the cylinder head of an engine.
However, routing an oil drain tube through a cylinder head creates packaging issues. More specifically, pushrods and other valve train components are difficult to avoid, especially if the oil drain tube is not securely anchored inside the engine in such a manner so as to eliminate positional movement. Further, difficulties also arise in installing a long rigid drain tube inside the engine. For example, it is difficult to maneuver and position the oil drain tube within the engine and connecting it to the air/oil separation unit. It may also be difficult to find an area inside the cylinder head or crankcase that would allow for the installation of fasteners for mounting or attaching the oil drain tube to the cylinder head or crankcase. Therefore, there exists a need for a mechanism to secure an oil drain tube to an existing structural component in a cost-effective manner.